Sunday, 19 October 2014

Brian Madge Alice class Hunslet part 9 - positioning the boiler fittings.

The boiler/saddletank casting needs to be drilled for the boiler fittings, that is the chimney, water filler, dome and safety valve assembly. Of course the casting is suitable for a variety of different small Hunslets, some of which had domes, and some of which didn't, so casting dimples for the filler and dome would mean that the dimples could be in the wrong place according to the loco modelled. I'm modelling Velinheli, which is fitted with a dome.

To find the correct postion for the filler and dome I had to do a little maths...
I started by finding a good side view, luckily there's an excellent photo in the April 2013 issue of Railway Bylines (volume 18 issue 5).
I took the measurement of the top of the saddletank from the photograph, then divided it by the measurement of the model's saddletank to give me a ratio to divide by (133 / 23.7 = 5.61).
Then I measured the position of the centre of the water filler from the tank front on the photo, and divided that by that ratio (36 / 5.61 = 6.42).
The same was then done to find the dome position from the tank rear (45 / 5.61 = 8.02), and the position of the safety valve, which is slightly offset to the rear.


Now I had the relevant measurements I could drill the casting, easily done with the Unimat set up as a drill press and the casting held in a machine vice;


Well, if you've got the tools use them!

Here's the boiler fittings sitting in place;

 

Note that the dome and safety valves have yet to be properly fettled and seated.

My apologies if my terminology is incorrect, but I'm not a mathematician! Comments welcome.
I'm also aware that I could have just set the dome and filler positions by eye, but this has been a usefull exercise.

Paul.
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7 comments:

  1. Iain Robinson19 October 2014 at 20:45

    I gazed upon the blogger alert, noticed there was a new Hunslet Post and a smile cracked the wizened visage. Then I saw that it contained those works of the devil, numbers. So I will never be able to build a Hunslet because of the numbers...oh and I haven't got a Unimat...that lets me off the hook nicely.

    This is, as always, clever stuff. I note the insouciant way you claim that you don't know anything about numbers. You just made them march to your tune, Paul!

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    Replies
    1. Paul B.19 October 2014 at 20:57

      Numbers, Unimats, all quite unnecessary really Iain. I'd probably get things done a lot quicker if I stopped messing about and just got on with building the kit, as I said I could have just positioned things by eye and been done with it!
      But where would the fun be in that?
      More time wasting to come...

      Delete
  2. Mark21 October 2014 at 13:42

    Nice to see some more progress on the hunslet. Sometimes I wish I had a few more tools, as at least that way I'd be more likely to correctly align the boiler fittings than I do by eye. Certainly if I had the tools you do I'd be using them.

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    Replies
    1. Paul B.21 October 2014 at 15:43

      Its nice to be able to make progress again Mark! The past couple of months have been rather hectic at work, so I've been doing loads of overtime whilst I can (70+ hour weeks at one stage...).
      I like tools. I like buying them and I like using them. And they're usually a much better investment that yet another kit that will sit in the cupboard. (Says the man with a cupboard full of kits!).
      It has occured to me that boiler fittings can be aligned by turning the loco on its side and using a scribing block to mark out the centreline. But then you'd need a scribing block...

      Delete
  3. Mikkel22 October 2014 at 06:44

    Oooh, nice and shiny Hunslet. I've been reading back through the posts on this one, some very clever work, I think. The Unimat does seem to widen the scope of modelling and scratchbuilding quite a bit.

    I had to look up what a scribing block is, but I bet we'll see one in these pages soon? ;-)

    That calculator does have a certain 1980s look to it!

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    Replies
    1. Paul B.22 October 2014 at 15:54

      Thanks Mikkel. Yes, the Unimat does allow me to do things which I could only have dreamed of before, and there's a lot more jobs lined up for it.

      Scribing blocks are worth keeping an eye out for, they're very usefull for marking out handrail positions on loco boilers for example. A good secondhand one would be a usefull purchase.

      I can't remember the last time that I needed a new battery in that calculator, its probably been using the same one for 20+ years!

      Delete
    2. Paul B.22 October 2014 at 19:22

      I Googled 'Casio LC-310', made in 1981 apparently. I now feel very old, but at least my calculator has vintage cool!

      Delete

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